Light-emitting material comprising orthometalated iridium complex, light-emitting device, high efficiency red light-emitting device, and novel iridium complex

ABSTRACT

A synthesis method of a compound represented by formula (23), the method comprising reacting at least one of a ligand and a dissociation product thereof with an iridium compound at a room temperature or at an elevated temperatures in the presence or absence of a solvent or in the presence or absence of a base:

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of pending U.S. application Ser. No.12/725,025 filed on Mar. 16, 2010, which is a continuation of U.S.application Ser. No. 11/802,492 filed May 23, 2007, which is acontinuation of U.S. application Ser. No. 10/844,394 filed on May 13,2004, now U.S. Pat. No. 7,238,437, which is a divisional of U.S.application Ser. No. 09/747,933 filed Dec. 27, 2000 now U.S. Pat. No.6,821,645, the disclosures of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light-emitting material (i.e., alight-emitting device material) and light-emitting device capable ofconverting electric energy to light which is then emitted and moreparticularly to a light-emitting device which can be preferably used invarious arts such as display device, display, backlight,electrophotography, illuminating light source, recording light source,exposure light source, reading light source, sign, advertising displayand interior. The present invention also relates to a novellight-emitting material which can be expected to find application invarious arts.

2. Description of the Related Art

Today, various display devices have been under active study anddevelopment. In particular, an organic electric field light-emitting(EL) device can emit with a high luminance at a low voltage and thus hasbeen noted as a favorable display device. For example, a light-emittingdevice having a vacuum-deposited thin organic layer has been known(Applied Physics Letters, vol. 51, page 913, 1987). The light-emittingdevice described in this reference comprises as an electron-transportingmaterial tris(8-hydroxyquinolinate) aluminum complex (Alq) which islaminated with a positive hole-transporting material (amine compound) toexhibit drastically improved light-emitting properties as compared withthe conventional single-layer type devices.

In recent years, the application of organic EL device to color displayhas been under active study. However, in order to develop a highperformance color display, it is necessary that the properties of blue,green and red light-emitting devices be each improved.

As a means for improving the properties of light-emitting devices therehas been reported a green light-emitting device utilizing the emissionof light from orthometalated iridium complex (Ir(ppy)₃:Tris-Ortho-Metalated Complex of Iridium (III) with 2-Phenylpyridine)(Applied Physics Letters 75, 4 (1999)). The foregoing device can attainan external quantum yield of 8%, which is higher than the limit of theexternal quantum yield of the conventional light-emitting devices, i.e.,5%. However, since the foregoing light-emitting device is limited togreen light-emitting device, the range within it can be applied as adisplay is narrow. It has thus been desired to develop light-emittingmaterials capable of emitting light having other colors.

Noting a red light-emitting device, many light-emitting devicescomprisingDCM(4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran)and its analogy have been reported. No devices having an externalquantum efficiency of more than 5% have been reported. If the externalquantum efficiency of 5%, which is considered to be the limit of theexternal efficiency of the conventional red light-emitting device, canbe surpassed, the development of high efficiency organic EL devicescapable of emitting light having various colors can make a greatprogress. It has thus been desired to develop such high efficiencyorganic EL devices.

On the other hand, an organic light-emitting device which can attainlight emission with a high luminance is one having a laminate ofvacuum-deposited organic material layers. The preparation of such adevice is preferably accomplished by a coating method from thestandpoint of simplification of production procedure, workability, areaattained, etc. However, the device prepared by the conventional coatingmethod is inferior to that prepared by vacuum evaporation methodparticularly in light-emitting efficiency. It has thus been desired todevelop a novel light-emitting material.

In recent years, various materials having fluorescence have been used invarious arts such as filter dye, color conversion filter, dye forphotographic material, sensitizing dye, dye for dyeing pulp, laser dye,fluorescent medicine for medical diagnosis and organic light-emittingmaterial. Thus, there is a growing demand for such a material. Newlight-emitting materials have been desired.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a light-emitting devicehaving good light-emitting properties, a light-emitting material whichcan form such a light-emitting device, and a novel light-emittingmaterial which can be used in various fields. (a first embodiment)

Another object of the present invention is to provide a redlight-emitting device having good light-emitting properties, alight-emitting material which can form such a light-emitting device, anda novel light-emitting material which can be used in various fields. (asecond embodiment)

The foregoing object of the invention can be accomplished by thefollowing means.

1. A light-emitting material comprising a compound having a partialstructure represented by the following formulae (1) to (10), (21), (22),or tautomer thereof:

wherein R¹ and R² each represent a substituent; and q¹ and q² eachrepresent an integer of from 0 to 4, with the proviso that the sum of q¹and q² is 1 or more

wherein Z¹¹ and Z¹² each represent a nonmetallic atom group required toform a 5- or 6-membered ring with at least one of carbon atom andnitrogen atom, said ring optionally having a substituent or forming acondensed ring with the other ring; Ln¹ represents a divalent group; Y¹represents a nitrogen atom or carbon atom; and b¹ represents a singlebond or double bond,

wherein Z²¹ and Z²² each represent a nonmetallic atom group required toform a 5- or 6-membered ring with at least one of carbon atom andnitrogen atom, said ring optionally having a substituent or forming acondensed ring with the other ring; Y² represents a nitrogen atom orcarbon atom; and b² represents a single bond or double bond,

wherein X²⁰¹, X²⁰², X²⁰³ and X²⁰⁴ each represent a nitrogen atom or C—Rand forms a nitrogen-containing heteroaryl 6-membered ring with —C═N—,with the proviso that at least one of X²⁰¹, X²⁰², X²⁰³ and X²⁰⁴represents a nitrogen atom; R represents a hydrogen atom or substituent;and Z²⁰¹ represents an atomic group for forming an aryl or heteroarylring,

wherein Z²⁰¹ and Z³⁰¹ each represent an atomic group for forming an arylor heteroaryl ring,

wherein Z²⁰¹ and Z⁴⁰¹ each represent an atomic group for forming an arylor heteroaryl ring,

wherein Z¹ represents an atomic group which forms a heteroaryl ring.

2. The light-emitting material according to item 1, which comprises thecompound represented by the formula (21) or (22), wherein said quinolinederivative ligand is formed by at least four rings.

3. A compound having a partial structure represented by the followingformula (4) or a tautomer thereof:

wherein Z¹¹ and Z¹² each represent a nonmetallic atom group required toform a 5- or 6-membered ring with carbon atom and/or nitrogen atom, saidring optionally having a substituent or forming a condensed ring withthe other ring; Ln¹ represents a divalent group; Y¹ represents anitrogen atom or carbon atom; and b¹ represents a single bond or doublebond.

4. A compound represented by the following formula (23) or (24):

wherein R¹¹ each represent a substituent; R¹³, R¹⁴ and R¹⁵ eachrepresent a hydrogen atom or substituent; m¹ represents an integer offrom 0 to 4; and m² represents an integer of from 0 to 6,

wherein R¹¹ and R¹² each represent a substituent; m¹ represents aninteger of from 0 to 4; m² represents an integer of from 0 to 6; Z²represents an atomic group which forms an aryl or heteroaryl ring; Z³represents an atomic group which forms a nitrogen-containing heteroarylring; and n¹ represents an integer of from 1 to 3.

5. An organic light-emitting device comprising a light-emitting layer ora plurality of thin organic compound layers containing a light-emittinglayer formed interposed between a pair of electrodes, wherein at leastone layer comprises a light-emitting material having a partial structurerepresented by the following formula (1) to (10), (21), (22) or atautomer thereof:

wherein R¹ and R² each represent a substituent; and q¹ and q² eachrepresent an integer of from 0 to 4, with the proviso that the sum of q¹and q² is 1 or more,

wherein Z¹¹ and Z¹² each represent a nonmetallic atom group required toform a 5- or 6-membered ring with at least one of carbon atom andnitrogen atom, said ring optionally having a substituent or forming acondensed ring with the other ring; Ln¹ represents a divalent group; Y¹represents a nitrogen atom or carbon atom; and b¹ represents a singlebond or double bond,

wherein z²¹ and Z²² each represent a nonmetallic atom group required toform a 5- or 6-membered ring with at least one of carbon atom andnitrogen atom, said ring optionally having a substituent or forming acondensed ring with the other ring; Y² represents a nitrogen atom orcarbon atom; and b² represents a single bond or double bond,

wherein X²⁰¹, X²⁰², X²⁰³ and X²⁰⁴ each represent a nitrogen atom or C—Rand forms a nitrogen-containing heteroaryl 6-membered ring with —C═N—,with the proviso that at least one of X²⁰¹, X³⁰², X²⁰³ and X²⁰⁴represents a nitrogen atom; R represents a hydrogen atom or substituent;and Z²⁰¹ represents an atomic group for forming an aryl or heteroarylring,

wherein Z²⁰¹ and Z³⁰¹ each represent an atomic group for forming an arylor heteroaryl ring,

wherein Z²⁰¹ and Z⁴⁰¹ each represent an atomic group for forming an arylor heteroaryl ring,

wherein Z¹ represents an atomic group which forms a heteroaryl ring.

6. An organic light-emitting device according to item 5, wherein atleast one layer consists essentially of the light-emitting material.

7. The light-emitting device according to item 5, wherein said layercomprising the light-emitting material is formed by a coating process.

8. An organic light-emitting device comprising a light-emitting layer ora plurality of thin organic compound layers containing a light-emittinglayer formed interposed between a pair of electrodes, wherein at leastone layer contains an orthometalated iridium complex, and said layercontaining an orthometalated iridium complex is formed by a coatingprocess.

9. An organic light-emitting device having an external quantumefficiency of 5% or more, and a λmax of light emitting of 590 nm ormore.

DETAILED DESCRIPTION OF THE INVENTION

The first embodiment of the present invention will be further describedhereinafter.

The compound according to the invention is a light-emitting materialcomprising an orthometalated iridium complex. “Orthometalated metalcomplex” is a generic term for a group of compounds as described in AkioYamamoto, “Yuki Kinzoku Kagaku- Kiso to Oyo- (Organic MetalChemistry—Fundamentals and Application)”, Shokabosha, pp. 150, 232,1982, H. Yersin, “Photochemistry and Photophysics of CoordinationCompounds”, Springer-Verlag, pp. 1-77, pp. 135-146, 1987, etc.

The valence of iridium in the orthometalated iridium complex is notspecifically limited but is preferably 3. The ligands constituting theorthometalated iridium complex are not specifically limited so far asthey can form an orthometalated complex. In practice, however, there maybe used, e.g., aryl group-substituted nitrogen-containing heterocyclicderivative (The aryl group substitutes for the nitrogen-containingheterocycle on the carbon atom adjacent to nitrogen atom. Examples ofthe aryl group include phenyl group, naphthyl group, anthryl group,phenanthryl group, and pyrenyl group. The aryl group may further form acondensed ring with other carbon rings or heterocycles. Examples of thenitrogen-containing heterocycle include pyridine, pyrimidine, pyrazine,pyridazine, quinoline, isoquinoline, quinoxaline, phthalazine,quinazoline, naphtholidine, cinnoline, perimidine, phenanthroline,pyrrole, imidazole, pyrazole, oxazole, oxadiazole, triazole,thiadiazole, benzimidazole, benzoxazole, and phenanthridine), heteroarylgroup-substituted nitrogen-containing heterocyclic derivative (Theheteroaryl group substitutes for the nitrogen-containing heterocycle onthe carbon atom adjacent to nitrogen atom. Examples of the heteroarylgroup include group containing the foregoing nitrogen-containingheterocyclic derivative, chenyl group, and furyl group),7,8-benzoquinoline derivative, phosphinoaryl derivative,phosphinoheteroaryl derivative, phosphinoxyaryl derivative,phosphinoxyheteroaryl derivative, aminomethylaryl derivative,aminomethylheteroaryl derivative, etc. Preferred among these ligands arearyl group-substituted nitrogen-containing aromatic heterocyclicderivative, heteroaryl group-substituted nitrogen-containing aromaticheterocyclic derivative, and 7,8-benzoquinoline derivative. Even moredesirable among these ligands are phenylpyridine derivative,chenylpyridine derivative, 7,8-benzoquinoline derivative, benzylpyridinederivative, phenylpyrazole derivative, phenylisoquinoline derivative,and phenyl-substituted derivative of azole having two or more nitrogenatoms. Particularly preferred among these ligands are chenylpyridinederivative, 7,8-benzoquinoline derivative, benzylpyridine derivative,phenylpyrazole derivative, phenyl isoquinoline derivative, andphenyl-substituted derivative of azole having two or more nitrogenatoms.

The compound of the invention may have ligands other than the ligandsrequired to form an orthometalated complex. Examples of the otherligands include various known ligands. Examples of these ligands includethose described in H. Yersin, “Photochemistry and Photophysics ofCoordination Compounds”, Springer-Verlag, 1987, Akio Yamamoto, “YukiKinzoku Kagaku- Kiso to Oyo- (Organic Metal Chemistry—Fundamentals andApplication)”, Shokabosha, 1982, etc. Preferred among these ligands arehalogen ligands (preferably chlorine ligand), nitrogen-containingheterocyclic ligands (e.g., bipyridyl, phenanthroline), and diketoneligands. Even more desirable among these ligands are chlorine ligand andbipyridyl ligand.

There may be used one or a plurality of kinds of ligands constitutingthe compound of the invention. The number of ligands in the complex ispreferably from 1 to 3, particularly from 1 or 2, more preferably 1.

The number of carbon atoms in the compound of the invention ispreferably from 5 to 100, more preferably from 10 to 80, even morepreferably from 14 to 50.

Preferred among the compounds of the invention having a partialstructure represented by the formulae (1) to (10) or tautomers thereofare those having a partial structure represented by the formulae (1),(2), (4) to (10) or tautomers thereof.

The compound having a partial structure represented by the formula (1)or tautomer thereof may have one iridium atom per molecule or may be aso-called binuclear complex having two or more iridium atoms permolecule. This compound may further contain other metal atoms. This canapply to the compounds having a partial structure represented by theformula (2) to (10) or tautomers thereof.

In the formula (3), R¹ and R² each represents a substituent. Thesuffixes q¹ and q² each represent an integer of from 0 to 4, with theproviso that the sum of q¹ and q² is 1 or more. When q¹ and q² each are2 or more, the plurality of R¹'s and R²'s may be the same or different.Examples of the group represented by R¹ or R² include alkyl group (alkylgroup preferably having from 1 to 30, more preferably from 1 to 20,particularly from 1 to 10 carbon atoms, e.g., methyl, ethyl, iso-propyl,tert-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl,cyclohexyl, trifluoromethyl, pentafluoroethyl)alkenyl group (alkenylgroup preferably having from 2 to 30 carbon atoms, more preferably from2 to 20 carbon atoms, particularly from 2 to 10 carbon atoms, e.g.,vinyl, allyl, 2-butenyl, 3-pentenyl), alkinyl group (alkinyl grouppreferably having from 2 to 30 carbon atoms, more preferably from 2 to20 carbon atoms, particularly from 2 to 10 carbon atoms, e.g.,propargyl, 3-pentinyl), aryl group (aryl group preferably having from 6to 30 carbon atoms, more preferably from 6 to 20 carbon atoms,particularly from 6 to 12 carbon atoms, e.g., phenyl, p-methylphenyl,naphthyl, anthranyl), amino group (amino group preferably having from 0to 30 carbon atoms, more preferably from 0 to 20 carbon atoms,particularly from 0 to 10 carbon atoms, e.g., amino, methylamino,dimethylamino, diethylamino, dibenzylamino, diphenylamino,ditollylamino), alkoxy group (alkoxy group preferably having from 1 to30 carbon atoms, more preferably from 1 to 20 carbon atoms, particularlyfrom 1 to carbon atoms, e.g., methoxy, ethoxy, butoxy, 2-ethylhexyloxy),aryloxy group (aryloxy group preferably having from 6 to 30 carbonatoms, more preferably from 6 to 20 carbon atoms, particularly from 6 to12 carbon atoms, e.g., phenyloxy, 1-naphthyloxy, 2-naphthyloxy),heteroaryloxy group (heteroaryloxy group preferably having from 1 to 30carbon atoms, more preferably from 1 to 20 carbon atoms, particularlyfrom 1 to 12 carbon atoms, e.g., pyridyloxy, pyrazyloxy, pyrimidyloxy,quinolyloxy), acyl group (acyl group preferably having from 1 to 30carbon atoms, more preferably from 1 to 20 carbon atoms, particularlyfrom 1 to 12 carbon atoms, e.g., acetyl, benzoyl, formyl, pivaloyl),alkoxycarbonyl group (alkoxycarbonyl group preferably having from 2 to30 carbon atoms, more preferably from 2 to 20 carbon atoms, particularlyfrom 2 to 12 carbon atoms, e.g., methoxycarbonyl, ethoxycarbonyl),aryloxycarbonyl group (aryloxycarbonyl group preferably having from 7 to30 carbon atoms, more preferably from 7 to 20 carbon atoms, particularlyfrom 7 to 12 carbon atoms, e.g., phenyloxycarbonyl), acyloxy group(acyloxy group preferably having from 2 to 30 carbon atoms, morepreferably from 2 to 20 carbon atoms, particularly from 2 to 10 carbonatoms, e.g., acetoxy, benzoyloxy), acylamino group (acylamino grouppreferably having from 2 to 30 carbon atoms, more preferably 2 to 20carbon atoms, particularly from 2 to 10 carbon atoms, e.g., acetylamino,benzoylamino), alkoxycarbonylamino group (alkoxycarbonylamino grouppreferably having from 2 to 30 carbon atoms, more preferably 2 to 20carbon atoms, particularly from 2 to 12 carbon atoms, e.g.,methoxycarbonylamino), aryloxycarbonylamino group (aryloxycarbonylaminogroup preferably having from 7 to 30 carbon atoms, more preferably 7 to20 carbon atoms, particularly from 7 to 12 carbon atoms, e.g.,phenyloxycarbonylamino), sulfonylamino group (sulfonylamino grouppreferably having from 1 to 30 carbon atoms, more preferably 1 to 20carbon atoms, particularly from 1 to 12 carbon atoms, e.g.,methanesulfonylamino, benzenesulfonylamino), sulfamoyl group (sulfamoylgroup preferably having from 2 to 30 carbon atoms, more preferably 2 to20 carbon atoms, particularly from 2 to 10 carbon atoms, e.g.,sulfamoyl,methylsulfamoyl, dimethylsulfamoyl, phenylsulfamoyl), carbamoyl group(carbamoyl group preferably having from 1 to 30 carbon atoms, morepreferably 1 to 20 carbon atoms, particularly from 1 to 12 carbon atoms,e.g., carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl),alkylthio group (alkylthio group preferably having from 1 to 30 carbonatoms, more preferably 1 to 20 carbon atoms, particularly from 1 to 12carbon atoms, e.g., methylthio, ethylthio), arylthio group (arylthiogroup preferably having from 6 to 30 carbon atoms, more preferably 6 to20 carbon atoms, particularly from 6 to 12 carbon atoms, e.g.,phenylthio), heteroarylthio group (heteroarylthio group preferablyhaving from 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms,particularly from 1 to 12 carbon atoms, e.g., pyridylthio,2-benzimizolylthio, 2-benzoxazoylthio, 2-benzthiazolylthio), sulfonylgroup (sulfonyl group preferably having from 1 to 30 carbon atoms, morepreferably 1 to 20 carbon atoms, particularly from 1 to 12 carbon atoms,e.g., mesyl, tosyl), sulfinyl group (sulfinyl group preferably havingfrom 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms,particularly from 1 to 12 carbon atoms, e.g., methanesulfinyl,benzenesulfinyl), ureide group (ureide group preferably having from 1 to30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly from1 to 12 carbon atoms, e.g., ureide, methylureide, phenylureide),phosphoric acid amide group (phosphoric acid amide group preferablyhaving from 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms,particularly from 1 to 12 carbon atoms, e.g., diethylphosphoric acidamide, phenylphosphoric acid amide), hydroxy group, mercapto group,halogen atom (e.g., fluorine atom, chlorine atom, bromine atom, iodineatom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamicacid group, sulfino group, hydrazino group, imino group, heterocyclicgroup (heterocyclic group preferably having from 1 to 30 carbon atoms,more preferably from 1 to 12 carbon atoms, and containing as heteroatoms nitrogen atom, oxygen atom and sulfur atom, e.g., imidazolyl,pyridyl, quinolyl furyl, chenyl, piperidyl, morpholino, benzoxazolyl,benzimidazolyl, benzthiazolyl), and silyl group (silyl group preferablyhaving from 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms,particularly from 3 to 24 carbon atoms, e.g., trimethylsilyl,triphenylsilyl). These substituents may be further substituted. R¹'s orR²'s may be connected to each other, or R¹ and R² may be connected toeach other to form a condensed ring structure.

R¹ and R² each are preferably an alkyl group, aryl group, alkoxy group,amino group, cyano group or a group which forms a condensed ringstructure when R¹ and R² are connected to each other. Preferred amongthese groups are alkyl group and group which forms a condensed ringstructure when R¹ and R² are connected to each other. The suffixes q¹and q² each are preferably 0, 1 or 2. More preferably, the sum of q¹ andq² is 1 or 2.

In the formula (4), Z¹¹ and Z¹² each represent a nonmetallic atom grouprequired to form a 5- or 6-membered ring which may have a substituent ormay further form a condensed ring with the other ring. Examples of thesubstituents include halogen atom, aliphatic group, aryl group,heterocyclic group, cyano, nitro, —OR¹⁰¹, —SR¹⁰², —CO₂R¹⁰³, —OCOR¹⁰⁴,—NR¹⁰⁵R¹⁰⁶, —CONR¹⁰⁷R¹⁰⁸, —SO₂R¹⁰⁹, —SO₂NR¹¹⁰R¹¹¹, —NR¹¹²CONR¹¹³R¹¹⁴,—NR¹¹⁵CO₂R¹¹⁶, —COR¹¹⁷, —NR¹¹⁸COR¹¹⁹, and —NR₁₂₀SO₂R¹²¹ in which R¹⁰¹,R¹⁰³, R¹⁰⁴, R¹⁰⁵, R¹⁰⁶, R¹⁰⁷, R¹⁰⁸, R¹⁰⁹, R¹¹⁰, R¹¹¹, R¹¹², R¹¹³, R¹¹⁴,R¹¹⁵, R¹¹⁶, R¹¹⁷, R¹¹⁸, R¹¹⁹, R¹²⁰, and R¹²¹ each are independently ahydrogen atom, aliphatic group or aryl group.

Preferred among the foregoing substituents are halogen atom, aliphaticgroup, aryl group, —OR¹⁰¹, —SR¹⁰², —NR¹⁰⁵R¹⁰⁶, —SO₂R¹⁰⁹,—NR¹¹²CONR¹¹³R¹¹⁴, NR¹¹⁵CO₂R¹¹⁶ and —NR¹²⁰SO₂R¹²¹. Even more desirableamong these substituents are halogen atom, aliphatic group, aryl group,—OR¹⁰¹, —SR¹⁰², —NR¹⁰⁵R¹⁰⁶ and —SO₂R¹⁰⁹. Still even more desirable amongthese substituents are halogen atom, alkyl group, aryl group, alkoxygroup, phenoxy group, and dialkylamino group. Still even more desirableamong these substituents are halogen atom, C₁₋₁₀ alkyl group, C₆₋₁₀ arylgroup, and C₁₋₁₀ alkoxy group. Most desirable among these substituentsare halogen atom, and C₁₋₄ alkyl group.

The term “aliphatic group” as used herein is meant to indicate an alkyl,alkenyl, alkinyl or aralkyl group.

A preferred example of the 5- or 6-membered ring formed by Z¹¹ and Z¹²is an aromatic ring or heterocyclic aromatic group. Examples of such anaromatic ring or heterocyclic aromatic group include furan ring,thiophene ring, imidazole ring, thiazole ring, oxazole ring, pyrrolering, pyrazole ring, 1,2,3-triazole ring, 1,2,4-triazole ring,selenazole ring, oxadiazole ring, thiadiazole ring, benzene ring,pyridine ring, pyrimidine ring, pyrazine ring, and pyridazine ring. Z¹¹is preferably a thiophene ring, imidazole ring, thiazole ring, oxazolering, pyrrole ring, pyrazole ring, benzene ring or pyridine ring, morepreferably a thiazole ring, pyrrole ring, benzene ring or pyridine ring,most preferably benzene ring, among the foregoing rings. Z¹² ispreferably an imidazole ring, thiazole ring, oxazole ring, pyrrole ring,pyrazole ring, 1,2,3-triazole ring, 1,2,4-triazole ring, pyridine ringor pyrimidine ring, more preferably an imidazole ring, thiazole ring,pyrrole ring, pyrazole ring, pyridine ring or pyrimidine ring, even morepreferably pyrazole ring or pyridine ring, among the foregoing rings.The number of carbon atoms in Z¹¹ and Z¹² are each preferably from 3 to40, more preferably from 3 to 30, particularly from 3 to 20.

Ln¹ represents a divalent group. Examples of the) divalent grouprepresented by Ln¹ include —C(R¹³¹)(R¹³²)—, —N(R¹³³)—, —O—, —P(R¹³⁴)—,and —S—. R¹³¹ and R¹³² each independently represent a hydrogen atom,halogen atom, aliphatic group, aryl group, heterocyclic group, cyanogroup, —OR¹⁴¹, —SR¹⁴², —CO₂R¹⁴³, —OCOR¹⁴⁴, —NR¹⁴⁵R¹⁴⁶, —CONR¹⁴⁷R¹⁴⁸,—SO₂R¹⁴⁹, —SO₂NR¹⁵⁰R¹⁵¹, —NR¹⁵²CONR¹⁵³R¹⁵⁴, —NR¹⁵⁵CO₂R¹⁵⁶, —COR¹⁵⁷,—NR¹⁵⁸COR¹⁵⁹ or —NR¹⁶⁰SO₂R¹⁶¹ in which R¹⁴¹, R¹⁴², R¹⁴³, R¹⁴⁴, R¹⁴⁵,R¹⁴⁶, R¹⁴⁷, R¹⁴⁸, R¹⁴⁹, R¹⁵⁰, R¹⁵¹, R¹⁵², R¹⁵³, R¹⁵⁴, R¹⁵⁵, R¹⁵⁶, R¹⁵⁷,R¹⁵⁸, R¹⁵⁹, R¹⁶⁰, and R¹⁶¹ each independently represent a hydrogen atom,aliphatic group or aryl group. R¹³³ represents an aliphatic group, arylgroup or heterocyclic group. R¹³⁴ represents an aliphatic group, arylgroup, heterocyclic group or —OR¹⁷¹ in which R¹⁷¹ represents a hydrogenatom, aliphatic group or aryl group.

Ln¹ is preferably —C(R¹³¹)(R¹³²)—, —O— or —S—, more preferably—C(R¹³¹)(R¹³²)— in which R¹³¹ and R¹³² each are a hydrogen atom,aliphatic group or aryl group, even more preferably —C(R¹³¹)(R¹³²)— inwhich R¹³¹ and R¹³² each are a hydrogen atom or C₁₋₄ alkyl group. Thenumber of carbon atoms in Ln¹ is preferably from 0 to 20, morepreferably from 0 to 15, particularly from 0 to 10.

Y¹ represents a nitrogen atom or carbon atom. When Y¹ is a nitrogenatom, b¹ represents a single bond. When Y¹ is a carbon atom, b¹represents a double bond.

In the formula (7), Z²¹ and Z²² each represent a nonmetallic atom grouprequired to form a 5- or 6-membered ring which may have a substituent ormay further form a condensed ring with the other ring. Examples of thesubstituents include halogen atom, aliphatic group, aryl group,heterocyclic group, cyano, nitro, —OR²⁰¹, —SR²⁰², —CO₂R²⁰³, —OCOR²⁰⁴,—NR²⁰⁵R²⁰⁶, —CONR²⁰⁷R²⁰⁸, —SO₂R²⁰⁹, —SO₂NR²¹⁰R²¹¹, —NR²¹²CONR²¹³R²¹⁴,—NR²¹⁵CO₂R²¹⁶, —COR²¹⁷, —NR²¹⁸COR²¹⁹, and —NR²²⁰SO²R²²¹ in which R²⁰¹,R²⁰², R²⁰³, R²⁰⁴, R²⁰⁵, R²⁰⁶, R²⁰⁷, R²⁰⁸, R²⁰⁹, R²¹⁰, R²¹¹, R²¹², R²¹³,R²¹⁴, R²¹⁵, R²¹⁶, R²¹⁷, R²¹⁸, R²¹⁹, R²²⁰, and R²²¹ each areindependently a hydrogen atom, aliphatic group or aryl group.

Preferred examples of the substituents on Z²¹ and Z²² are the same asthat of Z¹¹ and Z¹².

Examples of the 5- or 6-membered ring formed by Z²¹ include furan ring,thiophene ring, imidazole ring, thiazole ring, oxazole ring, pyrrolering, pyrazole ring, 1,2, 3-triazole ring, 1,2,4-triazole ring,selenazole ring, oxanediazole ring, thiadiazole ring, benzene ring,pyridine ring, pyrimidine ring, pyrazine ring, and pyridazine ring.Preferred among these rings are thiophene ring, imidazole ring, thiazolering, oxazole ring, pyrrole ring, pyrazole ring, benzene ring, andpyridine ring. Even more desirable among these rings are thiazole ring,pyrrole ring, benzene ring, and pyridine ring. Most desirable amongthese rings is benzene ring. Examples of Z²² include pyrazole ring,1,2,3-triazole ring, 1,2,4-triazole ring, and pyridazine ring. Mostdesirable among these rings is pyrazole ring. The number of carbon atomsin Z¹¹ and are each preferably from 3 to 40, more preferably from 3 to30, particularly from 3 to 20.

Y² represents a nitrogen atom or carbon atom. When Y² is a nitrogenatom, b² represents a single bond. When Y² is a carbon atom, b²represents a double bond.

In the formula (8), X²⁰¹, X²⁰², X²⁰³ and X²⁰⁴ each represent a nitrogenatom or C—R and forms a nitrogen-containing heteroaryl 6-membered ringwith —C═N—, with the proviso that at least one of X²⁰¹, X²⁰², X²⁰³ andX²⁰⁴ represents a nitrogen atom. The nitrogen-containing heteroaryl6-membered ring formed by X²⁰¹, X²⁰², X²⁰³ or X²⁰⁴ with —C═N— may form acondensed ring. R represents a hydrogen atom or substituent. Thesubstituents are as defined with reference to R¹ and R². Preferredexamples of the substituents include pyrazine, pyrimidine, pyridazine,triazine, quinoxaline, quinazoline, phthalazine, cinnoline, purine, andpteridine. Even more desirable among these substituents are pyrazine,pyrimidine, pyridazine, quinoxaline, quinazoline, phthalazine, andcinnoline. Z²⁰¹ represents an atomic group for forming an aryl orheteroaryl ring. The aryl ring formed by Z²⁰¹ is an aryl ring preferablyhaving from 6 to 30 carbon atoms, more preferably from 6 to 20 carbonatoms, particularly from 6 to 12 carbon atoms, e.g., phenyl group,naphthyl group, anthryl group, phenanthryl group, pyrenyl group. Thearyl group may further form a condensed ring with carbon rings orheterocycles. The heteroaryl ring represented by Z²⁰¹ is preferably aheteroaryl ring formed by carbon, nitrogen, oxygen and sulfur atoms,more preferably a 5- or 6-membered heteroaryl ring. The heteroaryl ringmay further form a condensed ring. The heteroaryl ring preferably hasfrom 2 to 30 carbon atoms, more preferably from 2 to 20 carbon atoms,particularly from 2 to 10 carbon atoms. Examples of the heteroaryl ringrepresented by Z²⁰¹ include pyridine, pyrimidine, pyrazine, pyridazine,quinoline, isoquinoline, quinoxaline, phthalazine, quinazoline,naphtholidine, cinnoline, perimidine, phenanthroline, pyrrole,imidazole, pyrazole, oxazole, oxadiazole, triazole, thiadiazole,benzimidazole, benzoxazole, phenanthridine, chenyl, and furyl. The ringformed by Z²⁰¹ is preferably an aryl ring.

In the formula (9), Z²⁰¹ is as defined in the formula (8). Z³⁰¹represents an atomic group for forming an aryl or heteroaryl ringcondensed to pyridine ring. The aryl ring or heteroaryl ring formed byZ³⁰¹ has the same meaning as that formed by Z²⁰¹ in the formula (8). Thering formed by Z³⁰¹ is preferably an aryl ring.

In the formula (10), Z²⁰¹ is as defined in the formula (8). Z⁴⁰¹represents an atomic group which forms an aryl or heteroaryl ringcondensed to pyridine ring. The aryl or heteroaryl ring formed by Z⁴⁰¹has the same meaning as that formed by Z²⁰¹ in the formula (8). The ringformed by Z⁴⁰¹ is preferably an aryl ring.

An even more desirable embodiment of the compound of the invention is acompound represented by any one of the following formulae (11) to (20).Particularly preferred among the compounds represented by the formulae(11) to (20) are those represented by the formulae (11), (12) and (19)to (20).

The formula (11) will be further described hereinafter. R¹¹ and R¹² eachrepresent a substituent. Examples of the substituent represented by R¹¹or R¹² include those described with reference to R¹ above.

R¹¹ and R¹² each are preferably an alkyl or aryl group, more preferablyan alkyl group.

The suffix q¹¹ represents an integer of from 0 to 2, preferably 0 or 1,more preferably 0. The suffix q¹² represents an integer of from 0 to 4,preferably 0 or 1, more preferably 0. When q¹¹ and q¹² each are 2 ormore, the plurality of R¹¹'s and R¹²'s may be the same or different ormay be connected to each other to form a condensed-ring.

L¹ represents a ligand. Examples of such a ligand include ligandsrequired to form the foregoing orthometalated iridium complexes andligands described with reference to other ligands. L¹ is preferably aligand required to form an orthometalated iridium complex,nitrogen-containing heterocyclic ligand, diketone ligand or halogenligand, more preferably ligand required to form an orthometalatediridium complex or bipyridyl ligand.

The suffix n¹ represents an integer of from 0 to 5, preferably 0. Thesuffix m¹ represents an integer of from 1 to 3, preferably 3. Thecombination of n¹ and m¹ is preferably such that the metal complexrepresented by the formula (4) is a neutral complex.

The formula (12) will be further described hereinafter. R²¹, n², m², andL² have the same meaning as R¹¹, n¹, m¹, and L¹, respectively. Thesuffix q²¹ represents an integer of from 0 to 8, preferably 0. Whenq^(n) is 2 or more, the plurality of R²¹'s may be the same or differentor may be connected to each other to form a condensed ring.

The formula (13) will be further described hereinafter. R³¹, R³², q³¹,q³², n³, m³, and L³ have the same meaning as R¹, R², q¹, q², n¹, m¹, andL¹, respectively.

The formula (14) will, be further described hereinafter. R³⁰¹ and R³⁰²each represent a substituent. The substituents represented by R³⁰¹ andR³⁰² have the same meaning as those described with reference to Z¹¹ andZ¹². The suffixes q³⁰¹ and q³⁰² each represent an integer of from 0 to4. When q³⁰¹ and q³⁰² each represent an integer of from 2 to 4, theplurality of R³⁰¹'s and R³⁰²'s may be the same or different. Thesuffixes q³⁰¹ and q³⁰² each are preferably 0, 1 or 2, more preferably 0or 1. The suffixes m¹⁰¹ and n¹⁰¹ and L¹⁰¹ have the same meaning as thesuffixes m¹ and n¹ and L¹, respectively.

The formula (15) will be further described hereinafter. L¹⁰² has thesame meaning as L¹. The suffix n¹⁰² represents an integer of from 0 to5, preferably from 1 to 5. The suffix m¹⁰² represents an integer of from1 to 6, preferably from 1 or 2. The combination of n¹⁰² and m¹⁰² ispreferably such that the metal complex represented by the formula (15)is a neutral complex.

The formula (16) will be further described hereinafter. L¹⁰³, n¹⁰³ andm¹⁰³ have the same meaning as L¹, n¹⁰², and m¹⁰², respectively.

The formula (17) will be further described hereinafter. R³⁰³ representsa substituent. The substituent represented by R³⁰³ has the same meaningas that described with reference to Z²¹, Z²³, q³⁰³, L¹⁰⁴, n¹⁰⁴, and m¹⁰⁴have the same meaning as Z²², q³⁰¹, L¹, n¹⁰¹, and m¹⁰¹, respectively.

The formula (18) will be further described hereinafter. In the formula(18), the ring formed by X²⁰¹, X²⁰², X²⁰³ and X²⁰⁴ with —C═N and itspreferred examples are as defined in the formula (8). Z²⁰¹ represents anatomic group required to form an aryl or heteroaryl ring as defined inthe formula (8). Preferred examples of Z²⁰¹, too, are as defined in theformula (8). The suffixes n²⁰¹ and m²⁰¹ and L²⁰¹ have the same meaningas the suffixes n¹ and m¹ and L¹, respectively.

In the formula (19), Z²⁰¹ and Z³⁰¹ and their preferred examples are asdefined in the formula (9). The suffixes n²⁰² and m²⁰² and L²⁰² have thesame meaning as the suffixes n¹ and m¹ and L¹, respectively.

In the formula (20), Z²⁰¹ and Z⁴⁰¹ and their preferred examples are asdefined in the formula (10). The suffixes n²⁰³ and m²⁰³ and L²⁰³ havethe same meaning as the suffixes n¹ and m² and L³ respectively.

The compound of the invention may be a so-called low molecular compoundhaving one repeating unit such as one represented by the formula (1) ormay be a so-called oligomer or polymer compound having a plurality ofrepeating units such as one represented by the formula (1) (having aweight-average molecular weight (in polystyrene equivalence) ofpreferably from 1,000 to 5,000,000, more preferably from 2,000 to1,000,000, even more preferably from 3,000 to 100,000). The compound ofthe invention is preferably a low molecular compound.

Examples of the compound to be used in the invention will be givenbelow, but the present invention should not be construed as beinglimited thereto.

The synthesis of the compound of the invention can be accomplished byany known method as disclosed in “Inorg. Chem.”, No. 30, page 1,685,1991, No. 27, page 3,464, 1988, No. 33, page 545, 1994, “Inorg. Chem.Acta.”, No. 181, page 245, 1991, “J. Organomet. Chem.”, No. 35, page293, 1987, “J. Am. Chem. Soc.”, No. 107, page 1,431, 1985, etc.

Some examples of synthesis of the compound of the invention will bedescribed below.

As mentioned below, hexahalogenated iridium (III) compound andhexahalogenated iridium (IV) compound can be used as starting materialsto synthesize the compound of the invention.

SYNTHESIS EXAMPLE 1 Synthesis of Exemplary Compound (1-25)

Into a three neck distillation flask were charged 5.22 g of K₃IrCl₆,16.9 g of 2-benzylpyridine and 50 ml of glycerol. The contents of theflask were then heated to an internal temperature of 200° C. withstirring in an argon atmosphere for 1 hour. Thereafter, the contents ofthe flask were cooled to an internal temperature of 40° C. To thematerial was then added 150 ml of methanol. The material was furtherstirred for 1 hour, and then subjected to filtration with suction toobtain a crystal which was then purified through silica gel columnchromatography to obtain 4.34 g of the desired exemplary compound (1-25)(yield: 770).

SYNTHESIS EXAMPLE 2 Synthesis of Exemplary Compound (1-24)

Into a three neck distillation flask were charged 5.64 g of theexemplary compound (1-25), 560 ml of chloroform and 10.0 g ofacetylacetone. To the contents was then added dropwise 20.1 ml of a 28%methanol solution of sodium methylate at room temperature with stirringin 20 minutes. After the termination of dropwise addition, the mixturewas then stirred at room temperature for 5 hours. The mixture was thenextracted with 40 ml of saturated brine and 400 ml of water. Theresulting chloroform phase was washed with a mixture of 300 ml ofsaturated brine and 30 ml of water four times, dried over anhydrousanhydrous sodium sulfate, and then concentrated through a rotaryevaporator. The resulting residue was then purified through silica gelcolumn chromatography to obtain 5.59 g of the desired exemplary compound(1-24) (yield: 89%).

SYNTHESIS EXAMPLE 3 Synthesis of Exemplary Compound (1-26)

Into a three neck distillation flask were charged 6.28 g of theexemplary compound (1-24), 15.5 g of 2-phenylpyridine and 63 ml ofglycerol. The contents of the flask were then heated to an internaltemperature of 170° C. with stirring in an argon atmosphere for 15minutes. Thereafter, the contents of the flask were cooled to aninternal temperature of 40° C. The mixture was then extracted with 500ml of chloroform, 40 ml of saturated brine and 400 ml of water. Theresulting chloroform phase was washed with a mixture of 40 ml ofsaturated brine and 400 ml of water four times, and then dried overanhydrous sodium sulfate. The material was then concentrated through arotary evaporator. The resulting residue was then purified throughsilica gel column chromatography to obtain 5.60 g of the desiredexemplary compound (1-26) (yield: 82%).

SYNTHESIS EXAMPLE 4 Synthesis of Exemplary Compound (1-29)

Into a three neck distillation flask were charged 5.64 g of theexemplary compound (1-25) and 560 ml of chloroform. Into the contents ofthe flask was blown carbon monoxide with stirring over an ice bath for10 minutes. The mixture was further stirred for 1 hour. The mixture wasthen extracted with 40 ml of saturated brine and 400 ml of water. Theresulting chloroform phase was washed with a mixture of 300 ml ofsaturated brine and 30 ml of water four times, dried over anhydroussodium sulfate, and then concentrated through a rotary evaporator. Theresulting residue was then purified through silica gel columnchromatography to obtain 4.38 g of the desired exemplary compound (1-29)(yield: 74%).

SYNTHESIS EXAMPLE 5 Synthesis of Exemplary Compounds (1-65) and (1-66)

To a solution of 1.35 g of K₃IrCl₆ in 25 ml of water were then added1.01 g of 3-chloro-6-phenylpyridazine and 100 ml f glycerin. The mixturewas heated to a temperature of 180° C. with stirring for 4 hours. Afterthe termination of reaction, the reaction solution was then allowed tocool. To the reaction solution was then added water. The resulting darkbrown solid was withdrawn by filtration, and then dried. To a solutionof the resulting solid in 1 l of chloroform were then added 2.5 g ofacetylacetone and 4.8 g of a 28% methanol solution of sodium methoxide.The reaction mixture was heated under reflux so that it was reacted for2 hours. After the termination of reaction, the reaction solution wasthen poured into 500 ml of water. The reaction solution was thenextracted with chloroform. The extract was dried over anhydrousmagnesium sulfate, and then concentrated. The resulting solid was thendeveloped through silica gel column chromatography. An orange-coloredfraction which had been first eluted was concentrated, recrystallizedfrom a mixture of chloroform and ethanol, and then dried to obtain 66 mgof the desired exemplary compound l-65. The compound thus obtained wasthen measured for solution fluorescent spectrum. As a result, thefluorescence was found to have λmax of 578 nm (CHCl₃). A reddishorange-colored fraction which had been subsequently eluted wasconcentrated, recrystallized from a mixture of chloroform and ethanol,and then dried to obtain 294 mg of the desired exemplary compound I-66.The compound thus obtained was then measured for solution fluorescentspectrum. As a result, the fluorescence was found to have λmax of 625 nm(CHCl₃).

The second embodiment of the present invention will be further describedhereinafter.

The light-emitting device is an organic light-emitting device having anexternal quantum efficiency of 5% or more and λmax of 590 nm or more.The organic light-emitting device to be used herein is not specificallylimited. In practice, however, an organic EL (electroluminescence)device.

The external quantum efficiency of the light-emitting device of theinvention is preferably 7% or more, more preferably 9% or more, evenmore preferably 11% or more, particularly 13% or more.

The light-emitting device of the invention emits light having λmax ofpreferably 593 nm or more, more preferably 596 nm or more, even morepreferably 599 nm or more from the standpoint of purity of red color.

The light-emitting device of the invention is preferably an devicecomprising a transition metal complex (preferably orthometalatedcomplex), more preferably an iridium complex or platinum complex, evenmore preferably an orthometalated iridium complex, particularly acompound having a partial structure represented by the following formula(21) or (22).

“Orthometalated metal complex” is a generic term for a group ofcompounds as described in Akio Yamamoto, “Yuki Kinzoku Kagaku- Kiso toOyo- (Organic Metal Chemistry—Fundamentals and Application)”,Shokabosha, pp. 150, 232, 1982, H. Yersin, “Photochemistry andPhotophysics of Coordination Compounds”, Springer-Verlag, pp. 1-77, pp.135-146, 1987, etc.

The light-emitting device of the invention preferably comprises a layercomprising a compound having an ionization potential of 5.9 eV or more(more preferably 6.0 eV or more), more preferably anelectron-transporting layer having an ionization potential of 5.9 eV ormore, provided interposed between the cathode and the light-emittinglayer.

The CIE chromaticity value x of light emitted from the light-emittingdevice of the invention is preferably 0.50 or more, more preferably 0.53or more, even more preferably 0.57 or more, particularly 0.60 or morefrom the standpoint of purity of red color.

The CIE chromaticity value y of light emitted from the light-emittingdevice of the invention is preferably 0.50 or less, more preferably 0.45or less, even more preferably 0.39 or less.

The half width of spectrum of emission from the light-emitting device ofthe invention is preferably 100 nm or less, more preferably 90 nm orless, even more preferably 80 nm or less, particularly 70 nm or lessfrom the standpoint of purity of red color.

The compound having a partial structure represented by the formula (21)or (22) will be further described hereinafter.

In the formula (22), Z¹ represents an atomic group which forms aheteroaryl ring. The heteroaryl ring represented by Z¹ is preferably aheteroaryl ring comprising carbon, nitrogen, oxygen and sulfur atoms,more preferably a 5- or 6-membered heteroaryl ring. The heteroaryl ringrepresented by Z¹ may further form a condensed ring. The heteroaryl ringrepresented by Z¹ preferably has from 2 to 30 carbon atoms, morepreferably from 2 to 20 carbon atoms, particularly from 2 to 10 carbonatoms. Examples of the heteroaryl ring represented by Z¹ includepyridine, pyrimidine, pyrazine, pyridazine, quinoline, isoquinoline,quinoxaline, phthalazine, quinazoline, naphtholidine, cinnoline,perimidine, phenanthroline, pyrrole, imidazole, pyrazole, oxazole,oxadiazole, triazole, thiazole, thiadiazole, benzimidazole, benzoxazole,benzthiazole, phenanthridine, thiophene, and furan.

The light-emitting device material defined in Item 16 or 17 has apartial structure represented by the formula (21) or (22). The quinolinering, phenyl ring and heteroaryl ring represented by the ligand may forma condensed ring and may have a substituent. Examples of thesesubstituents include those described with reference to R¹¹ and R¹² inthe formula (23).

The valency of iridium constituting the compound having a partialstructure represented by the formula (21) or (22) is not specificallylimited but is preferably 3. The foregoing compound may have one iridiumatom per molecule or may me a so-called binuclear complex having two ormore iridium atoms per molecule. The foregoing compound is preferablyone having one iridium atom per molecule. This compound may furthercontain other metal atoms but preferably is a compound having an iridiumcomplex alone.

The compound having a partial structure represented by the formula (21)or (22) may have various ligands. Examples of the other ligands includevarious known ligands. Examples of these ligands include those describedin H. Yersin, “Photochemistry and Photophysics of CoordinationCompounds”, Springer-Verlag, 1987, Akio Yamamoto, “Yuki Kinzoku Kagaku-Kiso to Oyo- (Organic Metal. Chemistry—Fundamentals and Application)”,Shokabosha, 1982, etc. Preferred among these ligands are halogen ligands(preferably chlorine ligand), nitrogen-containing heterocyclic ligands(more preferably aryl group-substituted nitrogen-containing derivative(The aryl group substitutes on the carbon atom adjacent to the nitrogenatom constituting the nitrogen-containing heterocyclic group. Examplesof the aryl group include phenyl group, naphthyl group, anthryl group,phenanthryl group, and pyrenyl group. The aryl group may further form acondensed ring with carbon rings or heterocyles. Examples of thenitrogen-containing heterocycle include pyridine, pyrimidine, pryazine,quinoline, isoquinoline, quinoxaline, phthalazine, quinazoline,naphtholidine, cinnoline, perymidine, phenanthroline, pyrrole,imidazole, pyrazole, oxazole, oxadiazole, triazole, thiadiazole,benzimidazole, benzoxazole, benzthiazole, and phenanthridine)heteroarylgroup-substituted nitrogen-containing heterocyclic derivative (Theheteroaryl group substitutes on the carbon atom adjacent to the nitrogenatom constituting the nitrogen-containing heterocyclic group. Examplesof the aryl group include the foregoing nitrogen-containing heterocyclicderivative, chenyl group, and furyl group), e g., as phenylpyridine,benzoquinoline, quinolinol, bipyridyl, phenanthroline), diketone ligand,carboxylic acid ligand, and PF₆ ligand. Preferred among these ligandsare aryl group-substituted nitrogen-containing heterocyclic derivative,and diketone ligand.

There may be used one or a plurality of kinds of ligands constitutingthe compound of the invention. The number of ligands in the complex ispreferably from 1 to 3, particularly from 1 or 2, more preferably 2.

The compound of the invention may be a neutral complex or ionic complexhaving a counter salt (e.g., chlorine ion, PF₆ ion, ClO₄ ion, quaternarysalt (e.g., tetrabutyl ammonium)), preferably neutral complex.

The number of carbon atoms in the compound of the invention ispreferably from 15 to 100, more preferably from 20 to 70, even morepreferably from 30 to 60.

Preferred embodiments of the compound of the invention are compoundsrepresented by the following formulae (23) and (24).

The formula (23) will be described hereinafter.

R¹¹ and R¹² each represent a substituent. R¹¹'s or R¹²'s may beconnected to own or each other to form a cyclic structure.

Examples of the substituents represented by R¹¹ and R¹² include alkylgroup (alkyl group preferably having from 1 to 30, more preferably from1 to 20, particularly from 1 to 10 carbon atoms, e.g., methyl, ethyl,iso-propyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl,cyclopentyl, cyclohexyl, trifluoromethyl, pentafluoroethyl), alkenylgroup (alkenyl group preferably having from 2 to 30 carbon atoms, morepreferably from 2 to 20 carbon atoms, particularly from 2 to 10 carbonatoms, e.g., vinyl, allyl, 2-butenyl, 3-pentenyl), alkinyl group(alkinyl group preferably having from 2 to 30 carbon atoms, morepreferably from 2 to 20 carbon atoms, particularly from 2 to 10 carbonatoms, e.g., propargyl, 3-pentinyl), aryl group (aryl group preferablyhaving from 6 to 30 carbon atoms, more preferably from 6 to 20 carbonatoms, particularly from 6 to 12 carbon atoms, e.g., phenyl,p-methylphenyl, naphthyl, anthranyl), amino group (amino grouppreferably having from 0 to 30 carbon atoms, more preferably from 0 to20 carbon atoms, particularly from 0 to 10 carbon atoms, e.g., amino,methylamino, dimethylamino, diethylamino, dibenzylamino, diphenylamino,ditollylamino), alkoxy group (alkoxy group preferably having from 1 to30 carbon atoms, more preferably from 1 to 20 carbon atoms, particularlyfrom 1 to carbon atoms, e.g., methoxy, ethoxy, butoxy, 2-ethylhexyloxy),aryloxy group (aryloxy group preferably having from 6 to 30 carbonatoms, more preferably from 6 to 20 carbon atoms, particularly from 6 to12 carbon atoms, e.g., phenyloxy, 1-naphthyloxy, 2-naphthyloxy),heteroaryloxy group (heteroaryloxy group preferably having from 1 to 30carbon atoms, more preferably from 1 to 20 carbon atoms, particularlyfrom 1 to 12 carbon atoms, e.g., pyridyloxy, pyrazyloxy, pyrimidyloxy,quinolyloxy), acyl group (acyl group preferably having from 1 to 30carbon atoms, more preferably from 1 to 20 carbon atoms, particularlyfrom 1 to 12 carbon atoms, e.g., acetyl, benzoyl, formyl, pivaloyl),alkoxycarbonyl group (alkoxycarbonyl group preferably having from 2 to30 carbon atoms, more preferably from 2 to 20 carbon atoms, particularlyfrom 2 to 12 carbon atoms, e.g., methoxycarbonyl, ethoxycarbonyl),aryloxycarbonyl group (aryloxycarbonyl group preferably having from 7 to30 carbon atoms, more preferably from 7 to 20 carbon atoms, particularlyfrom 7 to 12 carbon atoms, e.g., phenyloxycarbonyl), acyloxy group(acyloxy group preferably having from 2 to 30 carbon atoms, morepreferably from 2 to 20 carbon atoms, particularly from 2 to 10 carbonatoms, e.g., acetoxy, benzoyloxy), acylamino group (acylamino grouppreferably having from 2 to 30 carbon atoms, more preferably 2 to 20carbon atoms, particularly from 2 to 10 carbon atoms, e.g., acetylamino,benzoylamino), alkoxycarbonylamino group (alkoxycarbonylamino grouppreferably having from 2 to 30 carbon atoms, more preferably 2 to 20carbon atoms, particularly from 2 to 12 carbon atoms, e.g.,methoxycarbonylamino), aryloxycarbonylamino group (aryloxycarbonylaminogroup preferably having from 7 to 30 carbon atoms, more preferably 7 to20 carbon atoms, particularly from 7 to 12 carbon atoms, e.g.,phenyloxycarbonylamino), sulfonylamino group (sulfonylamino grouppreferably having from 1 to 30 carbon atoms, more preferably 1 to 20carbon atoms, particularly from 1 to 12 carbon atoms, e.g.,methanesulfonylamino, benzenesulfonylamino), sulfamoyl group (sulfamoylgroup preferably having from 2 to 30 carbon atoms, more preferably 2 to20 carbon atoms, particularly from 2 to 10 carbon atoms, e.g.,sulfamoyl, methylsulfaoyl, dimethylsulfamoyl, phenylsulfamoyl),carbamoyl group (carbamoyl group preferably having from 1 to 30 carbonatoms, more preferably 1 to 20 carbon atoms, particularly from 1 to 12carbon atoms, e.g., carbamoyl, methylcarbamoyl, diethylcarbamoyl,phenylcarbamoyl), alkylthio group (alkylthio group preferably havingfrom 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms,particularly from 1 to 12 carbon atoms, e.g., methylthio, ethylthio),arylthio group (arylthio group preferably having from 6 to 30 carbonatoms, more preferably 6 to 20 carbon atoms, particularly from 6 to 12carbon atoms, e.g., phenylthio), heteroarylthio group (heteroarylthiogroup preferably having from 1 to 30 carbon atoms, more preferably 1 to20 carbon atoms, particularly from 1 to 12 carbon atoms, e.g.,pyridylthio, 2-benzimizolylthio, 2-benzoxazoylthio,2-benzthiazolylthio),sulfonyl group (sulfonyl group preferably having from 1 to 30 carbonatoms, more preferably 1 to 20 carbon atoms, particularly from 1 to 12carbon atoms, e.g., mesyl, tosyl), sulfinyl group (sulfinyl grouppreferably having from 1 to 30 carbon atoms, more preferably 1 to 20carbon atoms, particularly from 1 to 12 carbon atoms, e.g.,methanesulfinyl, benzenesulfinyl), ureide group (ureide group preferablyhaving from 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms,particularly from 1 to 12 carbon atoms, e.g., ureide, methylureide,phenylureide), phosphoric acid amide group (phosphoric acid amide grouppreferably having from 1 to 30 carbon atoms, more preferably 1 to 20carbon atoms, particularly from 1 to 12 carbon atoms, e.g.,diethylphosphoric acid amide, phenylphosphoric acid amide), hydroxygroup, mercapto group, halogen atom (e.g., fluorine atom, chlorine atom,bromine atom, iodine atom), cyano group, sulfo group, carboxyl group,nitro group, hydroxamic acid group, sulfino group, hydrazino group,imino group, heterocyclic group (heterocyclic group preferably havingfrom 1 to 30 carbon atoms, more preferably from 1 to 12 carbon atoms,and containing as hetero atoms nitrogen atom, oxygen atom and sulfuratom, e.g., imidazolyl, pyridyl, quinolyl, furyl, chenyl, piperidyl,morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl), and silylgroup (silyl group preferably having from 3 to 40 carbon atoms, morepreferably 3 to 30 carbon atoms, particularly from 3 to 24 carbon atoms,e.g., trimethylsilyl, triphenylsilyl). These substituents may be furthersubstituted. R¹'s or R²'s may be connected to each other, or R¹ and R²may be connected to each other to form a condensed ring structure.

Preferred among these groups represented by R¹¹ and R¹² are alkyl group,aryl group, heteroaryl group, alkoxy group, halogen atom, cyano group,and cyclic structure obtained by the connection of R¹¹'s or R¹²'s to ownor each other. More desirable among these groups are alkyl group, arylgroup, and groups which are connected to each other to form an aromaticgroup. Even more desirable among these groups are alkyl group, andgroups which are connected to each other to form an aromatic group.

R¹³, R¹⁴ and R¹⁵ each represent a hydrogen atom or substituent. Examplesof the substituents represented by R¹³ and R¹⁵ include alkyl group,alkenyl group, alkinyl group, aryl group, heterocyclic group, and alkoxygroup which are the same as those described with reference to R¹¹ andR¹². Preferred among the groups represented by R¹³ and R¹⁵ are alkylgroup, aryl group, and heteroaryl group. More desirable among thesegroups is alkyl group.

Examples of the substituent represented by R¹⁴ include alkyl group,alkenyl group, alkinyl group, aryl group, heteroaryl group, heterocyclicgroup, and cyano group which are the same as those described withreference to R¹¹ and R¹². Preferred among the groups represented by R¹⁴are hydrogen atom, and alkyl group. More desirable among these groups ishydrogen atom.

The suffix m¹ represents an integer of from 0 to 4. The suffix m²represents an integer of from 0 to 6. When m¹ and m² are plural, theplurality of R¹¹'s and R¹²'s may be the same or different. The m¹ ispreferably from 0 to 2. The m² is preferably from 0 to 4, morepreferably from 0 to 2.

The formula (24) will be described hereinafter.

In the formula (4), R¹¹, R¹², m¹, and m² are as defined in the formula(23). Z² represents an atomic group which forms an aryl or heteroarylring. The aryl ring formed by Z² preferably has from 6 to 30 carbonatoms, more preferably from 6 to 20 carbon atoms, particularly from 6 to12 carbon atoms. Examples of the aryl group represented by Z² includephenyl group, naphthyl group, anthryl group, phenanthryl group, andpyrenyl group. Z² may further form a condensed ring with carbon rings orheterocycles. The heteroaryl ring represented by Z² is preferably aheteroaryl ring comprising carbon, nitrogen, oxygen and sulfur atoms,more preferably a 5- or 6-membered heteroaryl ring. The heteroaryl ringrepresented by Z² may further form a condensed ring. The heteroaryl ringrepresented by Z² preferably has from 2 to 30 carbon atoms, morepreferably from 2 to 20 carbon atoms, particularly from 2 to 10 carbonatoms. Examples of the heteroaryl ring represented by Z² includepyridine, pyrimidine, pyrazine, pyridazine, quinoline, isoquinoline,quinoxaline, phthalazine, quinazoline, naphtholidine, cinnoline,perimidine, phenanthroline, pyrrole, imidazole, pyrazole, oxazole,oxadiazole, triazole, thiadiazole, benzimidazole, benzoxazole,phenanthridine, chenyl, and furyl. The ring formed by Z² is preferablyan aryl ring.

Z³ represents an atomic group which forms a nitrogen-containingheterocycle with —C═N, preferably a nitrogen-containing heteroaryl ringcomprising carbon, nitrogen, oxygen and sulfur atoms, more preferably a5- or 6-membered heteroaryl ring. The nitrogen-containing heteroarylring represented by Z³ may further form a condensed ring. Thenitrogen-containing heteroaryl ring represented by Z³ preferably hasfrom 2 to 30 carbon atoms, more preferably from 2 to 20 carbon atoms,particularly from 2 to 10 carbon atoms. Examples of thenitrogen-containing heteroaryl ring represented by Z³ include pyridine,pyrimidine, pyrazine, pyridazine, quinoline, isoquinoline, quinoxaline,phthalazine, quinazoline, naphtholidine, cinnoline, perimidine,phenanthroline, pyrrole, imidazole, pyrazole, oxazole, oxadiazole,triazole, thiadiazole, benzimidazole, benzoxazole, benzthiazole, andphenanthridine.

The quinoline derivative ligand in the compound of the formula (21),(22), (23) or (24) is more preferably formed by at least four rings.

The compound of the invention may be a so-called low molecular compoundhaving one repeating unit such as one represented by the formula (21) or(22) or may be a so-called oligomer or polymer compound having aplurality of repeating units such as one represented by the formula (21)or (22) (having a weight-average molecular weight (in polystyreneequivalence) of preferably from 1,000 to 5,000,000, more preferably from2,000 to 1,000,000, even more preferably from 3,000 to 100,000). Thecompound of the invention is preferably a low molecular compound.

Examples of the compound of the invention will be given below, but thepresent invention should not be construed as being limited thereto.

The synthesis of the compound of the invention can be accomplished byany proper method. For example, various ligands or dissociation productsthereof and an iridium compound may be processed at room temperature orat elevated temperatures (heating by microwave, too, is effectivebesides normal heating) in the presence or absence of a solvent (e.g.,halogen-based solvent, alcohol-based solvent, ether-based solvent,water) or in the presence or absence of a base (e.g., various organicbases such as sodium methoxide, t-butoxy potassium, triethylamine andpotassium carbonate). As the starting materials there may be usediridium chloride (III), trisacetyl acetonate iridium (III), potassiumhexachloroiridate (III), potassium hexachloroiridate (IV), and analoguesthereof.

Some examples of the synthesis of the compound of the invention will begiven below.

SYNTHESIS EXAMPLE 1′ Synthesis of Compound (2-1)

1 g of 2-phenylquinoline, 0.71 g of iridium chloride (III), 40 ml of2-methoxy ethanol and 10 ml of water were mixed. The mixture was thenstirred at a temperature of 120° C. in a stream of nitrogen for 6 hours.The mixture was then cooled to room temperature. To the mixture was thenadded 50 ml of a 1 N aqueous solution of hydrochloric acid. The solidthus precipitated was then withdrawn by filtration. The solid thuswithdrawn was then purified through silica gel column chromatography(chloroform) to obtain a reddish brown solid. 0.1 g of the reddish brownsolid, 0.08 g of acetyl acetone, 0.15 ml of a 28 wt-% methanol solutionof sodium methoxide and 30 ml of chloroform were then mixed. The mixturewas then heated under reflux for 3 hours. The mixture was then cooled toroom temperature. The reaction solution was then purified through silicagel column chromatography (chloroform) to obtain 0.08 g of a red solid(2-1).

SYNTHESIS EXAMPLE 2′ Synthesis of Exemplary Compound (2-12)

To a solution of 0.65 g of K₃IrCl₆ in 12 ml of water were added 0.68 gof 2-(2-naphthyl)quinoline and 50 ml of glycerin. The mixture was thenheated to a temperature of 180° C. with stirring for 6 hours. After thetermination of reaction, the reaction solution was then allowed to cool.To the reaction solution was then added water. The resulting brown solidwas withdrawn by filtration, and then dried. Subsequently, the solidthus obtained was dissolved in 200 ml of chloroform. To the solutionthus obtained were then added 2.5 g of acetyl acetone and 4.8 g of a 28%methanol solution of sodium methoxide. The reaction solution was thenheated under reflux for reaction for 8 hours. After the termination ofreaction, the reaction solution was then poured into 300 ml of water.The reaction solution was then extracted with chloroform. The resultingextract was dried over anhydrous magnesium sulfate, and thenconcentrated to obtain a solid which was then developed through silicagel column chromatography (20:1 mixture of chloroform and methanol). Ared fraction thus eluted was concentrated, recrystallized from a mixtureof chloroform and ethanol, and then dried to obtain 330 mg of thedesired exemplary compound 2-12. The compound thus obtained was thenmeasured for solution fluorescent spectrum. The resulting fluorescencehad λmax of 656 nm (CHCl₃).

SYNTHESIS EXAMPLE 3′ Synthesis of Exemplary Compound (2-4)

The synthesis procedure of Synthesis Example 2′ was followed except thatthe ligand 2-(2-naphthyl)quinoline was replaced by2-(1-naphthyl)quinoline. Thus, the desired exemplary compound 1-4 wasobtained in an amount of 57 mg. The compound thus obtained was thenmeasured for solution fluorescent spectrum. The resulting fluorescencehad λmax of 644 nm (CHCl₃).

SYNTHESIS EXAMPLE 4′ Synthesis of Exemplary Compound (2-15)

30 mg of the exemplary compound (2-12) of the invention and 60 mg of2-phenylpyridine were added to 2 ml of glycerin. The mixture was thenheated to 200° C. with stirring for 3 hours. After the termination ofreaction, the reaction mixture was allowed to cool. To the reactionsolution was then added water. The reaction solution was then extractedwith chloroform. The resulting extract was dried over anhydrousmagnesium sulfate, and then concentrated to obtain a solid which wasthen developed through silica gel column chromatography with chloroform.An orange-colored fraction thus eluted was concentrated, recrystallizedfrom a mixture of chloroform and ethanol, and then dried to obtain 10 mgof the desired exemplary compound 2-15. The compound thus obtained wasthen measured for solution fluorescent spectrum. The resultingfluorescence had λmax of 646 nm (CHCl₃).

The light-emitting device comprising the compound of the invention (thefirst and second embodiments) will be further described hereinafter. Thelight-emitting device of the invention is not specifically limited inits system, driving method and form of utilization so far as itcomprises the compound of the invention. In practice, however, thelight-emitting device of the invention is preferably in the form ofstructure utilizing light emission from the compound of the invention orstructure comprising the compound of the invention ascharge-transporting material. A representative example of light-emittingdevice is an organic EL (electroluminescence) device.

The process for the formation of the organic layer in the light-emittingdevice comprising the compound of the invention is not specificallylimited. In practice, however, any method such as resistively-heatedvacuum evaporation method, electron beam method, sputtering method,molecular lamination method, coating method, ink jet method and printingmethod may be used. Preferred among these methods are resistively-heatedvacuum evaporation method and coating method from the standpoint ofproperties and producibility. More desirable among these methods iscoating method from the standpoint of prevention of thermaldecomposition during vacuum evaporation.

The light-emitting device of the invention comprises a light-emittinglayer or a plurality of thin organic compound layers containing alight-emitting layer formed interposed between a pair of electrodes,i.e., cathode and anode. There may be provided a positive hole-injectinglayer, a positive hole-transporting layer, an electron-injecting layer,an electron-transporting layer and a protective layer besides thelight-emitting layer. These layers may be provided with other functions.The various layers may be each made of various materials.

The anode supplies a positive hole into the positive hole-injectinglayer, positive hole-transporting layer, light-emitting layer, etc. Theanode may be made of a metal, alloy, metal oxide,electrically-conductive compound or mixture thereof, preferably amaterial having a work function of 4 eV or more. Specific examples ofsuch a material include electrically-conductive metal oxide such as tinoxide, zinc oxide, indium oxide and indium tin oxide (ITO), metal suchas gold, silver, chromium and nickel, mixture or laminate of such ametal and electrically-conductive metal oxide, electrically inorganicmaterial such as copper iodide and copper sulfate,electrically-conductive organic material such as polyaniline,polythiophene and polypyrrole, and laminate of these materials with ITO.Preferred among these materials are electrically-conductive metaloxides. Particularly preferred among these electrically-conductive metaloxides is ITO from the standpoint of producibility, electricalconductivity and transparency. The thickness of the anode may beproperly predetermined depending on its material. In practice, however,it is preferably from 10 nm to 5 μm, more preferably from 50 nm to 1 μm,even more preferably from 100 nm to 500 nm.

The anode is normally used in the form of anode layer formed onsoda-lime glass, non-alkali glass, transparent resin substrate or thelike. As the glass, if used, there is preferably used non-alkali glassto reduce the amount of ions to be eluted therefrom. Soda-lime glass, ifused, is preferably coated with a barrier such as silica. The thicknessof the substrate is not specifically limited so far as it suffices tomaintain a desired mechanical strength. In practice, however, it isnormally 0.2 mm or more, preferably 0.7 mm if glass is used.

The preparation of the anode may be accomplished by any method dependingon the materials used. If ITO is used for example, electron beam method,sputtering method, resistively-heated vacuum evaporation method,chemical reaction method (sol-gel method), method involving the coatingof a dispersion of indium tin oxide or the like can be used to form ananode layer.

The anode can be cleaned or otherwise treated to lower the drivingvoltage of the device or enhance the light emission efficiency of thedevice. The anode made of ITO, for example, can be effectively subjectedto UV-ozone treatment, plasma treatment, etc.

The cathode supplies electron into the electron-injecting layer,electron-transporting layer, light-emitting layer, etc. The cathode isselected taking into account the adhesivity to the layer adjacent to thenegative electrode such as electron-injecting layer,electron-transporting layer and light-emitting layer, ionizationpotential, stability, etc. As the material constituting the cathodethere may be used a metal, alloy, metal halide, metal oxide,electrically-conductive compound or mixture thereof. Specific examplesof such a material include alkaline metal (e.g., Li, Na, K) fluoridethereof, alkaline earth metal (e.g., Mg, Ca), fluoride thereof, gold,silver, lead, aluminum, sodium-potassium alloy, mixture thereof,lithium-aluminum alloy, mixture thereof, magnesium-silver alloy, mixturethereof, and rare earth metal such as indium and ytterbium. Preferredamong these materials are those having a work function of 4 eV or less.Even more desirable among these materials are aluminum, lithium-aluminumalloy, mixture thereof, magnesium-silver alloy, and mixture thereof. Thecathode may be not only in the form of single layer structure comprisingthe foregoing compound or mixture but also in the form of laminatedstructure comprising the foregoing compound or mixture. The thickness ofthe cathode may be properly predetermined depending on its material. Inpractice, however, it is preferably from 10 nm to 5 μm, more preferablyfrom 50 nm to 1 μm, even more preferably from 100 nm to 1 μm.

The preparation of the cathode can be accomplished by any method aselectron beam method, sputtering method, resistively-heated vacuumevaporation method and coating method. A single metal may bevacuum-vaporized. Alternatively, two or more components may bevacuum-vaporized at the same time. Further, a plurality of metals may bevacuum-vaporized to form an alloy electrode. Alternatively, an alloywhich has been previously prepared may be vacuum-vaporized.

The sheet resistivity of the anode and cathode is preferably as low aspossible and thus is preferably hundreds of ohm/□ or less.

As the material constituting the light-emitting layer there may be usedany material which can form a layer capable of injecting positive holefrom the anode, positive hole-injecting layer or positivehole-transporting layer as well as injecting electron from the cathode,electron-injecting layer or electron-transporting layer during theapplication of electric field, moving electron thus injected orproviding a site for the recombination of positive hole and electron foremission of light. Alternatively, any material which emits light fromeither singlet exciton or triplet exciton may be used. Examples of thelight-emitting material employable herein include various metalcomplexes such as metal complex and rare earth complex of benzoxazolederivative, benzoimidazole derivative, benzothiazole derivative,styrylbenzene derivative, polyphenyl derivative, diphenylbutadienederivative, tetraphenylbutadiene derivative, naphthalimide derivative,coumarine derivative, perylene derivative, perynone derivative,oxadiazole derivative, aldazine derivative, pyralidine derivative,cyclopentadiene derivative, bisstyrylanthracene derivative, quinacridonederivative, pyrrolopyridine derivative, thiadiazolopyridine derivative,cyclopentadiene derivative, styrylamine derivative, aromaticdimethylidine compound and 8-quinolinol derivative, polymer compoundsuch as polythiophene, polyphenylene and polyphenylenevinylene, organicsilane derivative, and the compound of the invention. The thickness ofthe light-emitting layer is not specifically limited but is normallyfrom 1 nm to 5 μm, preferably from 5 nm to 1 μm, even more preferablyfrom 10 nm to 500 nm.

The process for the formation of the light-emitting layer is notspecifically limited. In practice, however, any method such asresistively-heated vacuum evaporation method, electron beam method,sputtering method, molecular lamination method, coating method (e,g,spin coating method, casting method, dip coating method), ink jetmethod, LB method and printing method may be used. Preferred among thesemethods are resistively-heated vacuum evaporation method and coatingmethod.

As the material constituting the positive hole-injecting layer andpositive hole-transporting layer there may be used any material havingany of capability of injecting positive hole from the anode, capabilityof transporting positive hole and capability of giving barrier toelectron injected from the cathode. Specific examples of such a materialinclude electrically-conductive polymer oligomers such as carbazolederivative, triazole derivative, oxazole derivative, oxadiazolederivative, imidazole derivative, polyarylalkane derivative, pyrazolinederivative, pyrazolone derivative, phenylenediamine derivative,arylamine derivative, amino-substituted chalcone derivative,styrylanthracene derivative, fluorenone derivative, hydrazonederivative, stilbene derivative, silazane derivative, aromatic tertiaryamine compound, styrylamine compound, aromatic dimethylidine compound,porphyrin compound, polysilane compound, poly(N-vinylcarbazole)derivative, aniline copolymer, thiophene oligomer and polythiophene,organic silane derivative, carbon film, and the compound of theinvention. The thickness of the positive hole-injecting layer andpositive hole-transporting layer is not specifically limited but ispreferably from 1 nm to 5 μm, more preferably from 5 nm to 1 μm, evenmore preferably from 10 nm to 500 nm. The positive hole-injecting layerand positive hole-transporting layer each may be in the form of singlelayer structure made of one or more of the foregoing material ormulti-layer structure consisting of a plurality of layers having thesame or different compositions.

The formation of the positive hole-injecting layer and positivehole-transporting layer can be accomplished by any method such as vacuumevaporation method, LB method, method involving the coating of asolution or dispersion of the foregoing positive hole-injecting ortransporting material in a solvent (e.g., spin coating method, castingmethod, dip coating method), ink jet method and printing method. In thecase of coating method, the foregoing positive hole-injecting ortransporting material may be dissolved or dispersed in a solvent with aresin component. Examples of such a resin component include polyvinylchloride, polycarbonate, polystyrene, polymethyl methacrylate, polybutylmethacrylate, polyester, polysulfone, polyphenylene oxide,polybutadiene, poly(N-vinylcarbazole), hydrocarbon resin, ketone resin,phenoxy resin, polyamide, ethyl cellulose, vinyl acetate, ABS resin,polyurethane, melamine resin, unsaturated polyester resin, alkyd resin,epoxy resin, and silicon resin.

As the material constituting the electron-injecting material layer andelectron-transporting layer there may be used any material having any ofcapability of injecting electron from the cathode, capability oftransporting electron and capability of giving barrier to positive holeinjected from the anode. Specific examples of such a material includevarious metal complexes such as metal complex of heterocyclictetracarboxylic anhydride such as triazole derivative, oxazolederivative, oxadiazole derivative, fluorenone derivative,anthraquinodimethane derivative, anthrone derivative, diphenylquinonederivative, thiopyranedioxide derivative, carbodiimide derivative,fluorenilidenemethane derivative, distyrylpyrazine derivative andnaphthaleneperylene, phthalocyanine derivative and 8-quinolinolderivative and metal complex comprising metal phthalocyanine,benzoxazole or benzothiazole as a ligand, organic silane derivative, andthe compounds of the present invention. The thickness of theelectron-injecting layer and electron-transporting layer is notspecifically limited but is preferably from 10 nm to 500 nm, morepreferably from 5 nm to 1 μm, even more preferably from 10 nm to 500 nm.The electron-injecting layer and electron-transporting layer each may bein the form of single layer structure made of one or more of theforegoing material or multi-layer structure consisting of a plurality oflayers having the same or different compositions.

The formation of the electron-injecting layer and electron-transportinglayer can be accomplished by any method such as vacuum evaporationmethod, LB method, method involving the coating of a solution ordispersion of the foregoing positive hole-injecting or transportingmaterial in a solvent (e.g., spin coating method, casting method, dipcoating method), ink jet method and printing method. In the case ofcoating method, the foregoing positive hole-injecting or transportingmaterial may be dissolved or dispersed in a solvent with a resincomponent. As the resin component there may be used any of thoseexemplified with reference to the positive hole-injecting ortransporting layer.

As the material constituting the protective layer there may be used anymaterial capable of preventing materials which accelerating thedeterioration of the device such as water content and oxygen fromentering into the device. Specific examples of such a material includemetal such as In, Sn, Pb, Au, Cu, Ag, Al, Ti and Ni, metal oxide such asMgO, SiO, SiO₂, Al₂O, GeO, NiO, CaO, BaO, Fe₂O₂, Y₂O, and TiO₂, metalfluoride such as MgF₂, LiF, AlF, and CaF₂, polyethylene, polypropylene,polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene,polychlorotrifluoroethylene, polydichlorofluoroethylene, polymer ofchlorotrifluoroethylene with dichlorodifluoroethylene, copolymerobtained by the copolymerization of tetrafluoroethylene with a monomermixture comprising at least one comonomer, fluorine-containing copolymerhaving a cyclic structure in the copolymer main chain, water-absorbingmaterial having a water absorption of 1% or more, and moisture-resistantmaterial having a water absorption of 0.1% or less.

The process for the formation of the protective layer is notspecifically limited. Examples of the method employable herein includevacuum evaporation method, sputtering method, reactive sputteringmethod, MBE (molecular beam epitaxy) method, cluster ion beam method,ion plating method, plasma polymerization method (high frequency excitedion plating method), plasma CVD method, laser CVD method, heat CVDmethod, gas source CVD method, coating method, and printing method.

Specific embodiments of implication of the invention will be describedhereinafter, but the present invention should not be construed as beinglimited thereto.

COMPARATIVE EXAMPLE 1

40 mg of a poly(N-vinylcarbazole), 12 mg of PBD(2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole) and 1 mg of thefollowing compound A were dissolved in 2.5 ml of dichloroethane. Thesolution thus obtained was then spin-coated onto a substrate which hadbeen cleaned (1,500 rpm, 20 sec). The thickness of the organic layerthus formed was 98 nm. A patterned mask (arranged such that thelight-emitting area was 4 mm×5 trim) was then disposed on the thinorganic layer. Magnesium and silver were then simultaneouslyvacuum-evaporated onto the thin organic layer at a ratio of 10:1 to athickness of 50 nm in a vacuum metallizer. Silver was thenvacuum-evaporated onto the metal deposit to a thickness of 50 nm. Usinga Type 2400 source measure unit produced by TOXO TECHNICA CO., LTD., ado constant voltage was then applied to the EL device thus prepared tocause the emission of light which was then measured for luminance andwavelength by means of a Type BM-8 luminance meter produced by TOPCONCORP. and a Type PMA-11 spectral analyzer produced by HamamatsuPhotonics Co., Ltd., respectively. As a result, it was found that greenlight having λmax of 500 nm had been emitted. The external quantum yieldaround 100 cd/m²was then calculated. The results were 0.1%. The specimenwas then allowed to stand in a nitrogen atmosphere for 1 hour. As aresult, the specimen was visually observed to have numerous dark spotson the light-emitting surface thereof.

EXAMPLE 1

A device was prepared in the same manner as in Comparative Example 1except that the compound (1-1) was used instead of the compound A. As aresult, green light having λmax of 510 nm was emitted. The externalquantum yield around 100 cd/m² was 2.9%. The specimen was then allowedto stand in a nitrogen atmosphere for 1 hour. As a result, the specimenwas visually observed to have a small number of dark spots on thelight-emitting surface thereof.

EXAMPLE 2

A device was prepared in the same manner as in Comparative Example 1except that the compound (1-2) was used instead of the compound A. As aresult, green light having λmax of 510 nm was emitted. The specimen wasthen allowed to stand in a nitrogen atmosphere for 1 hour. As a result,the specimen was visually observed to have no dark spots on thelight-emitting surface thereof.

EXAMPLE 3

A device was prepared in the same manner as in Comparative Example 1except that the compound (1-3) was used instead of the compound A. As aresult, orange-colored light having λmax of 590 nm was emitted. Thespecimen was then allowed to stand in a nitrogen atmosphere for 1 hour.As a result, the specimen was visually observed to have no dark spots onthe light-emitting surface thereof.

EXAMPLE 4

A device was prepared in the same manner as in Comparative Example 1except that the compound (1-4) was used instead of the compound A. As aresult, green light having λmax of 510 nm was emitted. The specimen wasthen allowed to stand in a nitrogen atmosphere for 1 hour. As a result,the specimen was visually observed to have no dark spots on thelight-emitting surface thereof.

EXAMPLE 5

A device was prepared in the same manner as in Comparative Example 1except that the compound (1-20) was used instead of the compound A. As aresult, green light having λmax of 547 nm was emitted. The specimen wasthen allowed to stand in a nitrogen atmosphere for 1 hour. As a result,the specimen was visually observed to have no dark spots on thelight-emitting surface thereof.

EXAMPLE 6

A device was prepared in the same manner as in Comparative Example 1except that the compound (1-24) was used instead of the compound A. As aresult, green light having λmax of 530 nm was emitted. The specimen wasthen allowed to stand in a nitrogen atmosphere for 1 hour. As a result,the specimen was visually observed to have no dark spots on thelight-emitting surface thereof.

EXAMPLE 7

A device was prepared in the same manner as in Comparative Example 1except that the compound (1-25) was used instead of the compound A. As aresult, light having λmax of 564 nm was emitted. The specimen was thenallowed to stand in a nitrogen atmosphere for 1 hour. As a result, thespecimen was visually observed to have no dark spots on thelight-emitting surface thereof.

EXAMPLE 8

A device was prepared in the same manner as in Comparative Example 1except that the compound (1-36) was used instead of the compound A. As aresult, green light having λmax of 520 nm was emitted. The specimen wasthen allowed to stand in a nitrogen atmosphere for 1 hour. As a result,the specimen was visually observed to have no dark spots on thelight-emitting surface thereof.

EXAMPLE 9

A device was prepared in the same manner as in Comparative Example 1except that the compound (1-41) was used instead of the compound A. As aresult, green light having λmax of 513 nm was emitted. The externalquantum yield around 100 cd/m² was 5.1%. The specimen was then allowedto stand in a nitrogen atmosphere for 1 hour. As a result, the specimenwas visually observed to have no dark spots on the light-emittingsurface thereof.

EXAMPLE 10

A device was prepared in the same manner as in Comparative Example 1except that the compound (1-42) was used instead of the compound A. As aresult, green light having λmax of 535 nm was emitted. The specimen wasthen allowed to stand in a nitrogen atmosphere for 1 hour. As a result,the specimen was visually observed to have no dark spots on thelight-emitting surface thereof.

EXAMPLE 11

A device was prepared in the same manner as in Comparative Example 1except that the compound (1-44) was used instead of the compound A. As aresult, orange-colored light having λmax of 532 nm was emitted. Thespecimen was then allowed to stand in a nitrogen atmosphere for 1 hour.As a result, the specimen was visually observed to have no dark spots onthe light-emitting surface thereof.

EXAMPLE 12

A device was prepared in the same manner as in Comparative Example 1except that the compound (1-46) was used instead of the compound A. As aresult, yellow light having λmax of 568 nm was emitted. The specimen wasthen allowed to stand in a nitrogen atmosphere for 1 hour. As a result,the specimen was visually observed to have no dark spots on thelight-emitting surface thereof.

EXAMPLE 13

A device was prepared in the same manner as in Comparative Example 1except that the compound (1-65) was used instead of the compound A. As aresult, yellowish orange-colored light having λmax of 578 nm wasemitted. The specimen was then allowed to stand in a nitrogen atmospherefor 1 hour. As a result, the specimen was visually observed to have nodark spots on the light-emitting surface thereof.

EXAMPLE 14

A device was prepared in the same manner as in Comparative Example 1except that the compound (1-66) was used instead of the compound A. As aresult, reddish orange-colored light having λmax of 625 nm was emitted.The specimen was then allowed to stand in a nitrogen atmosphere for 1hour. As a result, the specimen was visually observed to have no darkspots on the light-emitting surface thereof.

EXAMPLE 15

An ITO substrate which had been cleaned was put in a vacuum metallizer.α-NPD(N,N′-diphenyl-N,N′-di(α-naphthyl)-benzidine) was thenvacuum-evaporated onto the ITO substrate to a thickness of 40 nm. Thefollowing compound B and the compound (1-46) of the invention were thensimultaneously vacuum-evaporated onto the substrate at a ratio of 10:1to a thickness of 24 nm. The following compound C was thenvacuum-evaporated onto the substrate to a thickness of 24 nm. Apatterned mask (arranged such that the light-emitting area was 4 mm×5mm) was then disposed on the thin organic layer. Magnesium and silverwere then simultaneously vacuum-evaporated onto the thin organic layerat a ratio of 10:1 to a thickness of 250 nm in the vacuum metallizer.Silver was then vacuum-evaporated onto the metal deposit to a thicknessof 250 nm. A dc constant voltage was then applied to the EL device thusprepared to cause the emission of light. As a result, it was found thatyellow light having λmax of 567 nm had been emitted and the externalquantum efficiency had been 13.6% (185 cd/m².hr).

EXAMPLE 16

An ITO substrate which had been cleaned was put in a vacuum metallizer.α-NPD(N,N′-diphenyl-N,N′-di(α-naphthyl)-benzidine) was thenvacuum-evaporated Onto the ITO substrate to a thickness of 40 nm. Thecompound (1-42) of the invention were then vacuum-evaporated onto thesubstrate to a thickness of 20 nm. The compound C was thenvacuum-evaporated onto the substrate to a thickness of 40 nm. Apatterned mask (arranged such that the light-emitting area was 4 mm×5mm) was then disposed on the thin organic layer. Magnesium and silverwere then simultaneously vacuum-evaporated onto the thin organic layerat a ratio of 10:1 to a thickness of 250 nm in the vacuum metallizer.Silver was then vacuum-evaporated onto the metal deposit to a thicknessof 250 nm. A dc constant voltage was then applied to the EL device thusprepared to cause the emission of light. As a result, it was found thatgreenish yellow light having λmax of 535 nm had been emitted and theexternal quantum efficiency had been 3.1% (120 cd/m².hr).

EXAMPLE 17

40 mg of a poly(N-vinylcarbazole), 12 mg ofPBD(2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole) and 1 mg of thecompound (1-4) of the invention were dissolved in 2.5 ml ofdichloroethane. The solution thus obtained was then spin-coated onto asubstrate which had been cleaned (1,500 rpm, 20 sec). The thickness ofthe organic layer thus formed was 98 nm. The compound C was thenvacuum-evaporated onto the organic layer to a thickness of 40 nm in avacuum metallizer. A patterned mask (arranged such that thelight-emitting area was 4 mm×5 mm) was then disposed on the thin organiclayer. Lithium fluoride was then vacuum-evaporated onto the material toa thickness of 5 nm in the vacuum metallizer. Aluminum was thenvacuum-evaporated onto the material to a thickness of 500 nm. A dcconstant voltage was then applied to the EL device thus prepared tocause the emission of light. As a result, it was found thatorange-colored light having λmax of 580 nm had been emitted. Theexternal quantum efficiency was 4.2% (1,000 cd/m²).

EXAMPLE 18

Baytron P (PEDOT-PSS solution (polyethylenedioxythiophene-polystyrenesulfonic acid-doped material) produced byBayer Inc.) was spin-coated onto a substrate which had been cleaned(1,000 rpm, 30 sec), and then dried at a temperature of 150° C. in vacuofor 1.5 hours. The thickness of the organic layer thus formed was 70 nm.40 mg of a poly(N-vinylcarbazole) and 1 mg of the compound (1-42) of theinvention were dissolved in 2.5 ml of dichloroethane. The solution thusobtained was then spin-coated onto the foregoing substrate which hadbeen cleaned (1,500 rpm, 20 sec). A patterned mask (arranged such thatthe light-emitting area was 4 mm×5 mm) was then disposed on the thinorganic layer. Magnesium and silver were then simultaneouslyvacuum-evaporated onto the thin organic layer at a ratio of 10:1 to athickness of 250 nm in a vacuum metallizer. Silver was thenvacuum-evaporated onto the metal deposit to a thickness of 250 nm. A dcconstant voltage was then applied to the EL device thus prepared tocause the emission of light. As a result, it was found that yellowishgreen light having λmax of 540 nm had been emitted. The external quantumefficiency was 6.2% (2,000 cd/m²).

EL devices comprising compounds of the invention were prepared andevaluated in the same manner as mentioned above. As a result, highefficiency EL devices capable of emitting light having various colorswere prepared. These EL devices were confirmed to have excellentdurability. Further, vacuum-metallized doped devices comprisingcompounds of the invention can emit light at a high efficiency. Devicescomprising a single layer made of a light-emitting material of theinvention, too, can emit light at a high efficiency.

The compound of the invention can be used as an organic EL material. Thecompound of the invention can also be used to prepare a high efficiencyand durability EL device capable of emitting light having variouscolors.

COMPARATIVE EXAMPLE 2

α-NPD(N,N′-diphenyl-N,N′-di(α-naphthyl)-benzidine) was vacuum-evaporatedonto an ITO substrate which had been cleaned to a thickness of 40 nm.The following compounds A′ and B′ were then simultaneouslyvacuum-evaporated onto the substrate at a ratio of 10:1 to a thicknessof 24 nm. The compound C′ was then vacuum-evaporated onto the metaldeposit. A patterned mask (arranged such that the light-emitting areawas 4 mm×5 mm) was then disposed on the thin organic layer. Magnesiumand silver were then simultaneously vacuum-evaporated onto the thinorganic layer at a ratio of 10:1 to a thickness of 250 nm in a vacuummetallizer. Silver was then vacuum-evaporated onto the metal deposit toa thickness of 50 nm. Using a Type 2400 source measure unit produced byTOYO TECHNICA CO., LTD., a dc constant voltage was then applied to theEL device thus prepared to cause the emission of light which was thenmeasured for luminance and wavelength by means of a Type BM-8 luminancemeter produced by TOPCON CORP. and a Type PMA-11 spectral analyzerproduced by Hamamatsu Photonics Co., Ltd., respectively. As a result, itwas found that green light having λmax of 516 nm and CIE chromaticityvalue (x, y) of 0.29 and 0.62 had been emitted. The external quantumefficiency was 13.6% (478 cd/m²).

COMPARATIVE EXAMPLE 3

α-NPD(N,N′-diphenyl-N,N′-di(α-naphthyl)-benzidine) was vacuum-evaporatedonto an ITO substrate which had been cleaned to a thickness of 40 nm.Alq (trisquinonate aluminum) andDCM(4-(Dicyanomethylene)-2-methyl-6-(4-dimethylamino styryl)-4H-pyran)were then simultaneously vacuum-evaporated onto the substrate at a ratioof 100:1 to a thickness of 60 nm. The substrate was then cathodicallyvacuum-metallized in the same manner as in Comparative Example 1 toprepare a device As a result, reddish orange-colored light having λmaxof 597 nm and CIE chromaticity value (x, y) of 0.54 and 0.44 had beenemitted. The external quantum efficiency was 0.89% (248 cd/m²). The halfwidth of emission spectrum was 92 nm.

EXAMPLE 19

A device was prepared in the same manner as in Comparative Example 2except that the compound (2-1) was used instead of the compound B′. As aresult, red light having λmax of 599 nm and CIE chromaticity value (x,y) of 0.60 and 0.39 had been emitted. The external quantum efficiencywas 13.4% (252 cd/m²). The half width of emission spectrum was 69 nm.

EXAMPLE 20

A device was prepared in the same manner as in Comparative Example 2except that the compound (2-12) was used instead of the compound B′. Asa result, red light having λmax of 623 nm and CIE chromaticity value (x,y) of 0.65 and 0.34 had been emitted. The external quantum efficiencywas 10.9% (379 cd/m²). The half width of emission spectrum was 75 nm.

EXAMPLE 21

40 mg of a poly(N-vinylcarbazole), 12 mg of PBO(2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole) and 1 mg of thecompound (2-1) of the invention were dissolved in 2.5 ml ofdichloroethane. The solution thus obtained was then spin-coated onto asubstrate which had been cleaned (1,500 rpm, 20 sec). The thickness ofthe organic layer thus formed was 20 nm. A patterned mask (arranged suchthat the light-emitting area was 4 mm×5 mm) was then disposed on thethin organic layer. Magnesium and silver were then simultaneouslyvacuum-evaporated onto the thin organic layer at a ratio of 10:1 to athickness of 250 nm in a vacuum metallizer. Silver was thenvacuum-evaporated onto the metal deposit to a thickness of 250 nm. A dcconstant voltage was then applied to the EL device thus prepared tocause the emission of light which was then measured for luminance,emission spectrum and voltage-current characteristics. As a result, itwas found that orange-colored light having λmax of 603 nm andchromaticity value (x, y) of 0.61 and 0.38 had been emitted. Theexternal quantum yield around 50 cd/m² was then calculated. The resultswere 5.0%.

EXAMPLE 22

A device was prepared in the same manner as in Example 21 except thatthe compound (2-4) was used instead of the compound (2-1). As a result,red light having λmax of 641 nm and CIE chromaticity value (x, y) of0.68 and 0.30 had been emitted. The external quantum yield around 50cd/m² was calculated. The results were 5.2%.

EXAMPLE 23

40 mg of a poly(N-vinylcarbazole), 12 mg ofPBD(2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole) and 1 mg of thecompound (2-12) of the invention were dissolved in 2.5 ml ofdichloroethane. The solution thus obtained was then spin-coated onto asubstrate which had been cleaned (1,500 rpm, 20 sec). The thickness ofthe organic layer thus formed was 110 nm. The compound C′ was thenvacuum-evaporated onto the organic layer to a thickness of 40 nm in avacuum metallizer. A patterned mask (arranged such that thelight-emitting area was 4 mm×5 mm) was then disposed on the thin organiclayer. Lithium fluoride was then vacuum-evaporated onto the thin organiclayer to a thickness of 5 nm in the vacuum metallizer. Aluminum was thenvacuum-evaporated onto the metal deposit to a thickness of 500 nm. A dcconstant voltage was then applied to the EL device thus prepared tocause the emission of light. As a result, it was found that red lighthaving λmax of 633 nm had been emitted. The external quantum efficiencywas 6.2% (1,000 cd/m²).

EXAMPLE 24

40 mg of a poly(N-vinylcarbazole), 12 mg of the following compound D′and 1 mg of the compound (2-12) of the invention were dissolved in 2-5ml of dichloroethane. The solution thus obtained was then spin-coatedonto a substrate which had been cleaned (3,000 rpm, 20 sec). Thesubstrate was then heated and dried in vacuo (100° C., 1 hour). Asolution of the compound C′ in 2.5 ml of n-butanol was then spin-coatedonto the substrate. The thickness of the organic layer thus formed was130 nm. A patterned mask (arranged such that the light-emitting area was4 mm×5 mm) was then disposed on the thin organic layer. Lithium fluoridewas then vacuum-evaporated onto the thin organic layer to a thickness of5 nm in the vacuum metallizer. Aluminum was then vacuum-evaporated ontothe metal deposit to a thickness of 500 nm. A dc constant voltage wasthen applied to the EL device thus prepared to cause the emission oflight. As a result, it was found that red light having λmax of 635 nmhad been emitted. The external quantum efficiency was 6.8% (2,000cd/m²).

EXAMPLE 25

A device was prepared in the same manner as in Comparative Example 1except that the compound (1-33) was used instead of the Compound A ofComparative Example 1. As a result, green light was emitted. Thespecimen was then allowed to stand in a nitrogen atmosphere for 1 hour.As a result, the specimen was visually observed to have no dark spots onthe light-emitting surface thereof.

EXAMPLE 26

A device was prepared in the same manner as in Comparative Example 1except that the compound (1-38) was used instead of the Compound A ofComparative Example 1. As a result, green light was emitted. Thespecimen was then allowed to stand in a nitrogen atmosphere for 1 hour.As a result, the specimen was visually observed to have no dark spots onthe light-emitting surface thereof.

EXAMPLE 27

A device was prepared in the same manner as in Comparative Example 1except that the compound (1-56) was used instead of the Compound A ofComparative Example 1. As a result, red light was emitted. The specimenwas then allowed to stand in a nitrogen atmosphere for 1 hour. As aresult, the specimen was visually observed to have no dark spots on thelight-emitting surface thereof.

EXAMPLE 28

A device was prepared in the same manner as in Comparative Example 1except that the compound (2-9) was used instead of the Compound A ofComparative Example 1. As a result, red light was emitted. The specimenwas then allowed to stand in a nitrogen atmosphere for 1 hour. As aresult, the specimen was visually observed to have no dark spots on thelight-emitting surface thereof.

EL devices comprising compounds of the invention can be prepared andevaluated in the same manner as mentioned above. Thus, high efficiencyred light-emitting devices can be prepared.

The high efficiency red light-emitting device according to the inventionhas a higher efficiency than the conventional red light-emittingdevices. Thus, the high efficiency red light-emitting device accordingto the invention is suitable for various arts such as display device,display, backlight, electrophotography, illuminating light source,recording light source, exposure light source, reading light source,sign, advertising display and interior. The high efficiency redlight-emitting device according to the invention can consume adrastically reduced power as compared with the conventional redlight-emitting organic EL devices having an external quantum yield ofless than 5%. The high efficiency red light-emitting device according tothe invention can also have an increased working area and be used overan extended period of time. Thus, the high efficiency red light-emittingdevice according to the invention can find wider application in the artof organic EL color display.

The compound of the invention can be used for medical use or asfluorescent brightening agent, photographic material, UV-absorbingmaterial, laser dye, color filter dye, color conversion filter, etc.

The entire disclosure of each and every foreign patent application fromwhich the benefit of foreign priority has been claimed in the presentapplication is incorporated herein by reference, as if fully set forth.

1. A synthesis method of a compound represented by following formula(23), the method comprising: reacting at least one of a ligand and adissociation product thereof with an iridium compound at a roomtemperature or at an elevated temperatures in the presence or absence ofa solvent or in the presence or absence of a base:

wherein R¹¹ and R¹² each represents a substituent; R¹³, R¹⁴ and R¹⁵ eachrepresents a hydrogen atom or a substituent; m¹ represents an integer offrom 0 to 4; and m² represents an integer of from 0 to
 6. 2. Thesynthesis method according to claim 1, which uses a mixed solvent of2-methoxyethanol and water as the solvent.
 3. The synthesis methodaccording to claim 1, wherein the reaction is conducted in a stream ofnitrogen.
 4. The synthesis method according to claim 1, furthercomprising: processing with an aqueous solution of hydrochloric acid. 5.The synthesis method according to claim 1, further comprising: purifyingthrough a silica gel column chromatography.
 6. The synthesis methodaccording to claim 1, which uses sodium methoxide as the base.